Pneumatic tire tube



J. w. WABER PNEUMATIC TIRE TUBE Filed Aug, 9' 1950 `une 2, 1931.

i (,Pa'tentedfllune l931` .unas w. wanna, or cnrcaeo, ILLINOIS /rNEUMA'rIcrrnn'l'rtmn imputation mea mgm 9, 1930.v serial No. '474,14g. f

same is inflated if punctured, the pressure loss.

from thepuncture is either entirely prevented or reduced to a minimum. -It also is designed to diminish the ordinary ,deiation action prevalent-inthe tires and tubes now in common use.- -f

A feature of my invention is the provision of a tube structure having an inner layer of elastic material whichis formed of a predetermined size which inner layer then has applied to the outer' circumference thereof a layer of mastic puncture healing material and an outer layer of elastic material, which structure is then cured in a mold of substantially the same size and shape as the inner contour of the casing whichreceives the tube.

Another feature of my'invention is to provide a puncture proof tube, the outer surface of which `is substantially the same shape or slightly larger than the inner surface of the casing with"which it is to be used, thus eliminating any stretching of the tube whenit is inflated.

Another feature of my inventionl is vide a puncture proof tube by the two-cure process; f

Another feature of my inventionis to provide va tube formed of layers of rubber of difl ferent densities which reduces the porosity of the tube.` For a more complete understanding of my invention reference may be had to the accompanying drawing, ensuing speciiication :jiji ap nded claims.

n the, drawings:

Fig; l shows lin cross-section the inner layer 5- s across-section -of an optional form to pro-v of elastic material molded to 'substantially of my complete tube, in which the outer layer ofvulcanized material extends approximately half wayaround the tube.

Balloon tires are usually constructed with thin sidewalls and they have large contact susceptible to puncture and stone bruises. Inner liners have been proposed butthese haveV been objectionable as they have been constituted in part offibre or fabric material which causes chafing and; rupturing of the casing. Inner tubes having compression members,`

area withthe road which has made the same f v etc. have been proposed but these have been.

unsatisfactory.

The full molded tube of my Jinvention Aof substantially the size and shape of the inner contour of the casing overcomes the objectionable features of prior tubes and provides a-tube which is very satisfactory as to con -struction and durability.

It will be apparent from the accompanying drawings and the following descriptlon that while many of the elements of design and process are familiar to the artof making rubber products, old elements and new have been marshalled together to produce a new and novel puncture proof or puncture sealing inner tube entirely distinct from anything heretofore produced, easy to fit and install in av casing, -easy to repair in case' of unusual injury,-1i1ore` efficient th`an previous tires,-

the usefulness of which will last for with little or no deterioration.

years The tube of the present invention is formed the same or nearly the same size and f shape ais-it will assume when inflated in the caslng and on the rim'. In other Words, so` shaped and sized that it suffers little or no ydistortion when in use and inflated and so made that'the part of the tube which, inuse,

underlies th'e'tread portieri of the casing is 'v nmuchfthickened, allowin for Ian annularl cavity throughout the thickened portion of" se'aling plastic compound that tightly-adheres/'to a nail or other puncturng object I the-tube, which 'cavity is filled'with a self when -it is Hforceifthrough the walls of the inner tube and the ,plastic material in the cavi ity so that the loss of pressure resulting from the pungtureis entirelyprevented in\ almost every case and in the few exceptions pressure loss is so reduced that it is negligible.

All of this tube with the exception of the plastic material in the cavity described, may be of ordinary tube stock. The bettergrades of tube stock now in vcommon use in the rubber industry will prove best in this tube and the poorer grades of stock result in poorer. tubes of this design and process.

The plastic material has two important characteristics ;-irst it must be adhesive, to adhere toy the puncturing instrument when the puncturing instrulnent is allowed to remain in the walls of the tube, and also to adhere to objects when withdrawn but not so adhesive as not t0 be strippedfrom the puncturing instrument whenit is withdrawn. In fact the plastic material is of just that degree of adhesiveness that when the nail yor puncturing object is withdrawn, the outer covering ofthe plastic material strips the plastic material from off fthe object with? drawn forming a plug for the hole made in the outer covering of the plastic material, thus preventing the loss of pressure in the tube, 1n either case. v

Another interesting and valuable contribution to the art of making punctureproofinner tubes was discovered and made use of in the manufacture of the present tube that cannt be readily shown in drawing but only described, and that is, when a tube made in the manner hereinafter setforth, has` an outer periphery slightly greater than the inner peri hery @of the casing in which it is to be use peripheral compression is proi ,duced which aids the process of 'sealing with vresultant prevention and reduction of delation for which purpose this tube has been invented.

To make an inner tube for the purposes and of the characteristics above described the following process has been Jfollowed Rubber stock was milled and compounded similar to that in general use in the rubber industry today. From this stock an inner tube is formed, the valve inserted, and the whole formed into an endless rubber `ring capable of some distention by having compressed air forced through the valve. The tube in this condition resembles the yordinary inner tube in 'general use partially inflated except that the tube need not be vulcanized.

From this point the process sharply differentiates from all other processes used in buildinginner tubes, or puncture proof, or

f puncture sealinginner tubes.

- dimensions or very nearly so.

Onthe tread portion of the tube which has been inflated andplaced on its form (a revolving form being best for the purpose) is placed a strip of plastic material with the characteristics above described. Because vof the adhesive characteristics 'of this mastic material it adheres tenaciously vto the inner tube becoming a component part thereof.

The next step in the process of building this tube is to take a piece of milled and compounded tube stock of apredetermined'l thickness (and compounded so that in the curing it will be timed to finish curing with the rest of the tube) and place it over. theplastic mate 'rial and extending farther -down on. the

the Acover sto'c'ks havediierent densities so that `when curing under heatand pressure the one stock is forced into the pores of f thev other and porosity therefore reducedto aminimum.A f'

It has also beenfound that the two stocks d have their time 'of cure balanced, the inside to cure faster and the outer` to cur-e, slower so that when the vcure is finally completed both layers will be properly vulcanized.

I have found by placing a strip of vulcanizable tube stock around the innerperiphery, thus thickeningup that portion of the tube usually protected by a ilap in common use, that a greatly improved tube is proics duced and the usual flap maybe dispensed f with.

After the tube is built up as above described it is placed 'in a mold of the predetermined size and'shape and heat lapplied and the inflation or internal pressure lncreased to an amount sufficient to insure a neat exterior when removed fromtthe -mold after it is fully cured. When the proper time has elapsed for vulcanizing the heat is Withdrawn and the finished tube removed from the mold which completes this proc'ess. v

However, this process` may be varied as follows:

1n this modified process the previously described process is followed up to the forming of the tube ready for the mastic or plastic material. In this modied process the inner or basic tube is cured or partially cured before the plastic material is applied thereto. In the modified process the basic tube is put in a curing moldof a predetermined 'size and shape and-partially or fully cured, after which itI is removed f rom the 5 vulcanized to the basic tube 10, thus forming mold, inflated to the'correct size and placed on the rform -and then the procedure followed in the first described process is carried out, this process varying from the first inasmuch as it is a two cure process while the 4former is a single cure process.` y

Referring more particularly to the drawings, I have shown a tube having a portionV 10 which may be formed ,of ordinary vulcanizable tube stock, a portion 12 com osed of a soft, sticky mastic material free o any curin agent, anda portion 11 of vulcanizable ruber similar to the portion 10 but which may be slightly thicker and also of a somewhat dilferent density.. In building the `present tube the basic tube portion'lO is irs't formed as an annularfen'dless tube of a size slightly smaller than the inner cavity of th'e casing with which it is to'be used. The ordinary valve stem (not shown) is next inserted in the tube 10,*and the basic tube 10 is inflated 'to the point where it isy fully expanded but.-

lnder substantially no tension. v In other words, it is inflated to about the size it will have when it is placed in use.

` The expanded tube 10 is mounted' on a building drum and the generally crescentshaped strip 'of mastic material 12 is placed about the tread portion or outer periphery thereof. The masticV material 12 is now covered by an outer layer 11 of vulcanizable rubber which extends beyond the edges of the mastic material 12 and is arranged tok be a closed pocket ithin which the mastic material is held. I desired,.the outer layer 11 of vulcanizable rubber may be extended entirely around the basic tube portion 10 so far asto forma thickened base portion '13 as disclosed in Fig. 2 of the drawings.

The completed tube structure is now placed in a mold of substantially the size and shape of the cavity within the casing andvulcanized as previously explained. v

In manufacturing puncture healing tubes I have heretoforejattempted to build. them on a-mandrel or core and then splice the ends which has produced very'unsatisfactoryV re- Y sults due to the diiculty of making the splice..

I have also attempted to place the mastic 12 and cover layer 11 on the basic tube 10 when in a collapsed condition','with theresult that'themastic material and the outer elastic vulcanizable covering have been uri-- tube was inflated. v In the present method Vof manufacture these diiculties are entirely overcc'imelan'd` '65 the puncture healing'materialjandouter elastic covering are' regularly and uniformly placed about the tube. ,'Also due to the fact that the entire tube structure may be built up before thetube is vulcanized, a tube which is without splices, seams or preciableoverlaps.

advantages which are' lwell knownto those who are familiar. witlfthe tube-making art.

It is believed that'it is impossibleto pracf tically or commercially manufacture a seamless, endless, annular fullymolded tube such as herein described ,without employing the air core which isV an important feature ofthe present invention.

While the drawings and the above descrip- -0 is formed. This type of tu, e has very marked, 7

t-ion disclose a particular form of my inven- 1. The method of const4 Acting aninner` tube for pneumatic tires ly which consists in forming Jan endless tube of vulcanizable rubber, expanding said tube by internal pressure,

attaching to the outer vcircumference of said tube while inflated, a layer of plastic sealing compound, covering the compound with/a vulcanizable rubber sheetwhich extends beyoud the edges-of the compound and contacts A I 'with the endless tube for adhesion thereto and curing the entire tube structure to produce a full molded tube.

2. The method of making an inner tube for endless tube ofvulca'nizable rubbeifv Lwhose dimensions areslightly smaller, than the cavity in the tire casing 'in which said tube is-in tended to be used, expanding said tube by in- I pneumatic tires which' consists informing an ternal pressure, applying to the outer circumference of said tube while inflated a layer of plastic'sealing compound, covering the said compound with ya layer of vulcanizable rubber which extends beyond the edges-of the compound and contacts with the endless tube for adhesion thereto and curing thesentire tube `structure in a mold whose cavity is substantiall equal to the size and shape `of the cavity o the tire casing in which said tube is intended to be used.

3. An inner tube f or pneumatic tires com-i prising a .basic inner layer, annular and tubui una lar, of vulcanizable rubber, an' outer cover layer of vulcanizablerubber, and a'layerof plastic l sealing compound interposed between said basic layer and said cover layer, the vlayers of said tube being full molded throughout the area coveredby the sealing' compound in -substantially the form and shape assumed under normal inflation and therefore substantially free from., strain or distortionlunder normal er being homogeneous throughoutytheir tacting portions when vulcanized.'

4f. An inner tube for pneumatic tires comprising'a basic inner layer, annular and tubular of vulcanizable rubber, an outer cover layer of vulcanizable rubber and a layer of plastic sealing compound interposed between Athe basic layer and said cover layer at a point overlying the tread portionjof the basic layer, the layers of said tube being full molded in substantially the form and shape assumed undernormal inflation and therefore substantially free from strain or distortion under normal inflation, the said basic layer and cover layer being homogeneous throughout their contacting ortions when vulcanized.

' 5. An inner tu e for pneumatic tires comprising a basic inner layer, annular and tubular, of vulcanizable rubber, an outer annular and tubular cover layer of vulcanizable rubber, and a layer of plastic sealing compound interposed between said basic layer and'said` cover layer, thelayers of said tube being full molded in substantially the form` and shape assumed under normal inflation and therefore substantially free fromstrain or distortion vunder normal inflation, the said4 basic layer and cover layer being homogeneous throughout their contacting portions when` vulcanized.

6. An inner tube for-pneumatic tires comprising a basic inner layer, annular and tubular, of vulanizable rubber, an outer cover layer of vulcanizable rubber, and a layer of plastic sealing compound interposed between said basic layer and said cover layer, said tube being full molded in substantially the form and shape assumed under normal inflation and when inflated to substantially fit the mold cavity will be approximately free of strain or distortion and will substantially fit the cavity of the/tine case in which it is intended to be used, and said outer layer overlying 'the plastic sealing compound and contacting and forming with the basic layer a homogeneous unit when vulcanized.

j 7. The method of constructing an inner tube for pneumatic tires which consists in expanding an endless rubber 'tube-by inter-- nal pressure, superimposiig upon the tread portion of said tube while sci-expanded a layer ofsplastic'sealing compound, then covering said compound with a vulcanjzable rubber sheet, land curing the entire tube structure While expanded in a mold, to produce a full v molded tube and cause the vulcanizable cbvering .sheet to become an integral part of the endless tube. j l y l Signed at Chicago, Illinois, this 4th day of August, 1930.

JAMES W.l WABER.' 

